Navigation procedure charts are used to assist in navigation of carrier vehicles such as airplanes, marine vessels (e.g. ships, boats, etc.), rail vehicles or trucking vehicles. For example, aeronautical charts, in particular, are used by pilots to gain an understanding of the geographic layout of an airport including the airport terminals as well as the surrounding vicinity of an airport which may include arrival and departure areas. Arrival and departure areas may, for example, cover an area within 100 miles of an airport. Aeronautical charts provide information that is particularly useful to pilots for take-off and landing of an airplane at an airport as well as approaches to and departures from an airport. Sets of aeronautical charts may be delivered to pilots or other personnel in various ways such as in paper form or in electronic form on a computer-readable storage device (such as a CD-ROM). Typically, the number of charts actually delivered may be very high, for instance, a new set of aeronautical charts may include hundreds or even many thousands of charts.
In order to accurately reflect geographic and procedural changes made relating to a terminal, its approaches and procedures, aeronautical charts are periodically updated with such changes. Thus, a customer of aeronautical charts (such as a pilot or other aircraft personnel) periodically will receive an entire new set of charts. A new set may, for example, be sent out on a computer-readable device, such as a CD-ROM, to customers every two to four weeks. The memory devices delivered to customers, for instance, may store thousands of aeronautical charts with some charts being changed and other charts left unchanged. Often, during a revision cycle a relatively small percentage of charts are changed; however, this may still amount to hundreds of aeronautical charts being changed out of the many thousands of charts delivered. The customer may selectively view and print out the stored charts from a computer device or view displayed charts on an airplane by placing the CD-ROM (or other memory device) in a portable computer device (such as a laptop computer) that is carried on the airplane itself.
Navigation procedure charts, such as aeronautical charts, have a significant amount of detail and are often technically complex. Thus, in many instances it may be difficult to determine which charts have changed between revision cycles. Furthermore, even if a navigation procedure chart is known to have been changed it is beneficial to be able to easily identify the chart elements that have been changed among the detailed information in the chart. Accordingly, there is a need to provide navigation procedure charts that easily identify changes that have been made from a past revision cycle.